#include "include\Common.fxh"

/*
% Ambient Light.
date: 05/29/12
*/
/*****************Un-Twealables**********************************/
#define FLIP_TEXTURE_Y 1

//after colon is a semantic usefull later for knowing what variables this shader has
float4x4 WorldViewProjection : WORLDVIEWPROJECTION 
<
	string UIWidget="None";
>;// < = annoation only for FXCOMPOSER 
float4x4 WorldInverseTranspose : WORLDINVERSETRANSPOSE <string UIWidget="None";>;
float4x4 World:WORLD <string UIWidget = "None";>;
float4x4 ViewInverse:VIEWINVERSE <string UIWidget = "None";>;

/****************Tweakables************************************/
texture ColorTexture : COLOR 
< 
	string ResouceName = "default_color.dds";
	string UIName = "Color Texture";
	string ResourceType = "2D";
>;

float4 AmbientColor : COLOR
<
	string UIName = "Ambient Light";
	string UIWidget = "Color";	
> = {1.0f,1.0f,1.0f,0.0f};

float3 LightDirection : DIRECTION 
<
	string Object = "DirectionalLight0";
	string UIName = "Light Direction";
	string Space = "World";
> = {0.0f , 0.0f, -1.0f};

float4 LightColor : DIFFUSE
<
	string UIName = "Light Color";
	string UIWidget = "Color";
> = {1.0f, 1.0f , 1.0f , 1.0f};

float3 FogColor
<
	string UIName = "Fog Color";
	string UIWidget = "Color";
> = {0.5f,0.5f,0.5f};

float FogStart = {20.0f};
float FogEnd = {40.0f};
bool FogEnabled = true;

/***************Un-Tweakable************************************/
sampler2D ColorSampler = sampler_state
{	
	Texture = <ColorTexture>; //the texture it will be grabbing pixel date from
	Magfilter = LINEAR;		  //zoom in - does linear interpelation
	Minfilter = LINEAR;		  //zoom out
	Mipfilter = LINEAR;
	AddressU = Wrap;		  //wrap or clamp
	AddressV = Wrap;		  //uv values or 0 to 1 oustide that they must either be wrapped(round up to the next) or clamped(made to fit in 0to1)
};

/*****************Data Structures****************************/
struct VS_INPUT
{
	float4 ObjectPosition: POSITION0;
	float2 TextureCoordinate : TEXCOORD0;
	float4 Normal:NORMAL0;
};

struct VS_OUTPUT
{
	float4 ScreenPosition: POSITION0;
	float2 TextureCoordinate: TEXCOORD0;
	float3 Normal : TEXCOORD1;	//no noraml symantic for outup of texture shader...not important simply storing a 4 float
	float3 LightDirection: TEXCOORD2;
	float FogAmount : TEXCOORD3;
};

struct PS_OUTPUT
{
	float4 Color:COLOR0;
};

/*****************Vertex Shader*****************************/
VS_OUTPUT vertex_shader(VS_INPUT IN)
{
	VS_OUTPUT OUT = (VS_OUTPUT)0; //memset clear garbage
	OUT.ScreenPosition = mul(IN.ObjectPosition, WorldViewProjection);
	OUT.TextureCoordinate = get_corrected_texture_coordinate(IN.TextureCoordinate);
	OUT.Normal = normalize(mul(IN.Normal, WorldInverseTranspose)); //place in the correct coordinate space
	OUT.LightDirection = normalize(-LightDirection); //want direction from vertex to light
	
	//FOG
	float4 worldPosition = mul(IN.ObjectPosition,World);
	float eyePosition = ViewInverse[3].xyz;
	OUT.FogAmount = get_fog_amount(eyePosition, worldPosition, FogStart, FogEnd);
	
	return OUT;
}

/*****************Pixel Shader*******************************/
PS_OUTPUT pixel_shader(VS_OUTPUT IN)
{
	PS_OUTPUT OUT = (PS_OUTPUT)0;
	
	float3 normal = normalize(IN.Normal);
	float3 lightDirection = normalize(IN.LightDirection);
	
	float4 color = tex2D(ColorSampler, IN.TextureCoordinate);
	float4 ambient = get_color_contribution(AmbientColor , color);
	float4 diffuse = get_color_contribution(LightColor,saturate(dot(lightDirection,normal))) * color;
	
	OUT.Color = ambient + diffuse;//more diffuses would be added here
	if(FogEnabled)
	{
		OUT.Color.rgb = apply_fog(FogColor, OUT.Color, IN.FogAmount);
	}
	return OUT;
}

/****************Techniques**********************************/
technique main
{
	pass p0 
	{
		VertexShader = compile vs_3_0 vertex_shader();
		PixelShader = compile ps_3_0 pixel_shader();
	}
}
